To: John Walliker who wrote (65308 ) 2/3/2001 7:10:52 PM From: Bilow Read Replies (1) | Respond to Hi John Walliker; By "Rambus BS", I meant BS by Rambus longs, not by the Rambus company themselves. That includes your own BS:I also think that radio frequency emissions would be a major problem with wide DDR buses. #reply-13386272Also, it will be much harder to obtain CE approval for DDR designs because of radio frequency emissions. #reply-13399937 Also: #reply-12510844I don't doubt that a closed box DDR system can be demonstrated, it's probably not too difficult. What I do doubt is whether an open box system can be made reliable when you have to allow for customers adding to or changing the memory modules, thermal problems, and power supply tolerances. (1) DDR went to SSTL-2 signalling, not CMOS. This means that voltage swings are drastically reduced (about half amplitude). Since EMI is typically proportional to something like the square of the voltage swing (with the same rise and fall times), this means that EMI is probably going to be easier with PC2100 than with PC100. The termination has been standardized and improved quite a bit. It still isn't as sweet as a decent ECL SSI board (I used to be in supercomputers), but the signal levels are beautiful and the EMI has been reduced. In short, the engineers learned from your PC100 EMI experience, and they took this into account. Also SSTL-2 uses relative threshold voltage levels instead of the ground reference. This helps make signal integrity less susceptible to ground bounce and reference problems, allowing lower voltage swings. This is not your daddy's TTL. #reply-14153814There was one valid point made by Carl in response to my post, that the change in signal levels in DDR will help reduce the EMC (radio interference) problems that happened with PC100. #reply-14157792But I get real disappointed when I think that this is likely to be yet another AMD mini launch: limited quantities, not likely to ship to Europe. Do you think those puppies (desktops w/ DDR in them), IF they do appear this week, will have the CE stamp on them? I once had to run through the EMR standards gauntlet for devices that come into human contact (for the CE stamp): it was tough. Maybe blow should wear his famous aluminum foil panties when he boots up the DDR system he is likely to receive for his valiant efforts! Spermatozoa (and oocytes) don't like EMR. I don't think it matters to hemaphrodites, tho'. LOL. #reply-14681000A lot of PC companies were put out of business in Europe when the CE mark became mandatory for EMR. That was without DDR. #reply-14681663BTW, what is the status of the EMR issue? (you may want to advise Scumbria to keep any pacemaker-enabled relatives away from his DDR home PC this holiday season.) Any boxes got CE approval yet? Those sure are hard to get. #reply-15076563Found same pacemaker warning on IBM pdf file on DDR memory #reply-15076911
